Even if you’re not a hardware person, you can connect external devices to your computer without fear. You only need a few hints to successfully solder your ZX80.
First, disconnect the power and video cables and remove the computer’s cover. With a pin or paper clip, push down on the centers of the plastic rivets holding the case together until their cores pop out. Flip the computer over, squeeze each rivet together, and push it out. Don’t lose these pieces! Turn the ZX80 back over and lift off its cover.
Strip about 1/8″-1/4″ of insulation off the end of the wire with wire strippers or a penknife. If the wire you want to solder is stranded (made out of several tiny wires inside the insulation), twirl the wires between your fingers to roll them into 1 thick wire. Tin the wire before you solder it to help get a good heat transfer and solder joint. (Tinning means melting a little solder with the iron onto the wire before using it.)
If you’re soldering onto a wire already on the board, bend the tinned exposed wire over your fingernail or around a small pliers into a hook. Hook the bent wire around the other wire on the board (not completely around–you might want to get it off some day).
Touch the iron to the joint to heat it and touch the solder to the hot joint, allowing it to melt. If the wire is light and the hook won’t stay where you put it, clip a wooden clothespin to the wire about an inch behind the exposed part. The heavy clothespin will keep tension on the hook and prevent it from slipping as you solder.
If your device doesn’t work when you finish, you may have a cold solder joint. To fix this, reheat the joint until the solder melts. Pull the wire gently to make firm contact with the component, then let solder cool.
Replace the cover and squeeze rivets together to fit them through their holes. Push a center pin into each rivet to secure it.